"What is Rigging and how does it fit within the production pipeline of a game?"

Rigging fits into the game production pipeline right after the character models have been finished.  The people rigging the models have to find a way to make animating the characters as neat, simple, and easy as possible for the animators. They must be able to have each of the characters that they rig be able to bend and move in a realistic believable way while not breaking or deforming the character.